I was trying to create a DOS bootable USB drive in for a BIOS update.
I have done the following twice, with the same result each time.
Then, with the same USB thumbdrive, I used Rufus on my neighbor's Windows 7 to make USB DOS bootable, and that worked.
1) Use GParted to partition USB drive and set boot flag.
2) Use UNetbootin to install FreeDOS on partitioned USB drive.
I followed the instructions with screen shots on:
https://unetbootin.github.io/
http://askubuntu.com/questions/46886/how-to-create-a-bootable-usb-stick-to-flash-a-bios
3) Attempt to Boot the PC to DOS:
Power > Restart F2 > BIOS, Boot order > Legacy > double click on USB Black screen opens with white flashing cursor. There is nothing else on the screen. Typing on keyboard doesn't show up on screen or move the cursor. alt+ctrl+del boots to Fedora.
fdisk -l indicates the boot flag is set (asterisk just after the Device name). From Fedora terminal:
$ sudo fdisk -l ... Disk /dev/sdb: 983 MiB, 1030750208 bytes, 2013184 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x696151a9 Device Boot Start End Sectors Size Id Type /dev/sdb1 * 2048 2013183 2011136 982M 6 FAT16
Operating system: Fedora 25, Linux kernel 4.8, Gnome 3.22.2
PC Hardware: Haswell Intel NUC Kit D54250WYK, Intel Core i5-4250U CPU
USB flash drive: 1.0 GB Drive VBTM Store 'n' Go
The preceding was posted on https://ask.fedoraproject.org/en/question/101997/dos-bootable-usb-drive-created-with-unetbootin-this-is-not-a-bootable-disk/
Where sideburns used Unetbootin to install FreeDOS on a flash drive and tried to boot it, twice.
Both times it failed giving error messages about a missing cable.
While I haven't tried all of the suggestions in these links, they at least sound useful:
FreeDOS 1.1 Bootable USB Image -- Linux
FlashBIOS -- Debian
DualBoot/FreeDOS -- Debian
Flashing BIOS from Linux -- ArchLinux
BIOS Update -- Gentoo
Creating a USB Bootable Storage Device Using FreeDOS -- Legacy Systems -- Dell